Python 3.4 Shutdown for Flexible Environment

The Python 3.4 runtime for the App Engine flexible environment will be shut down on
March 29, 2019. After this
date, new deployments to the App Engine flexible environment that request Python
version 3.4 will fail to deploy.

You must update to a newer version of Python before March 29, 2019. This will
help you avoid security risks that may result from the
end-of-life of Python 3.4
by the Python language community.

Migrating to a new Python version

To migrate to a newer Python version

Update the Cloud SDK with the latest updates by invoking the gcloud
command:

gcloud components update

Update the app.yaml for all versions of your application as follows:

runtime_config:
python_version: 3

where 3 means use the latest available Python version. Specify 3.5 to use
Python 3.5.5 or 3.6 to use Python 3.6.4.

Check the Python documentation for required code changes. The
What's New in 3.5
and the What's New in 3.6 provide
an overview of changes introduced in each of these newer versions..

Deploy your application. This is required to pick up the new changes.

Where to get help

If you run into any trouble migrating your application, and you have a support
package, you can get help through your normal support channel. If you don't have
a support package, respond to the email that you received notifying you about
the deprecation of Python 3.4.